Recently, damages of crops by long horned beetles tend to be increased. For example, Psacothea hilaris Pascore is parasitic on a mulberry tree and a fig tree, Anoplophora malasciaca Thomson is parasitic on a pear tree and an apple tree, and Acalolepla luxuriosa Bates is parasitic on an udo (Aralia cordata) to give big damages them. Furthermore, Monoehamus alternatus Hope and Semanotus japonicus Lacordaire are parasitic on trees. In particular, the damages of mulberry trees are large and spread over a wide range. Long horned beetles lay eggs under bark and the hatched larvae deeply make holes in the xylem to give eaten damages to the trees. The length of the eaten damage hole becomes longer than 60 cm. A mulberry tree having parasitic density loses its physiological function and is withered.
For exterminating long horned beetles, the use of chemical insecticides may be considered. However, since long horned beetles are hole-making vermin, a chemical insecticide is reluctant to reach the larvae in a trunk. Accordingly, it is difficult to effectively exterminate long horned beetles by chemical insecticides.
Also, since mulberry leaves are used for breeding silkworm, the use of a chemical insecticides gives undesirable influences on silkworm. Figs, pears, and apples are foods and hence the use of chemical insecticides for them give injuries to human bodies, animals and plants.
For solving these faults, it has been attempted to use mold fungi (e.g., Beauveria brongniartii (tenella)) which are natural enemy microorganisms to long horned beetles in place of chemical insecticides. Mold fungi are well parasitic on long horned beetles, in particular, on Psacothea hilaris Pascore but do not have phathogenity to silkworms. The extermination of long horned beetles using the mold fungi is performed by cultivating the mold fungi in a wheat bran culture medium and directly dusting the cultured fungi onto trees such as mulberry trees together with the culture medium. Dusting of the cultured fungi is practiced at the adult emergence period of long horned beetles. However, by the method described above, the cultured fungi are in a state near dormant cells since they cannot sufficiently imbibe culture medium components and hence the desired insecticidal effect of the mold fungi cannot be obtained. Furthermore, many of the dusted cultured fungi are absorbed by soil without attaching to trees, which also reduces the insecticidal efficiency. Also, even the fungi attached to trees are in danger of being washed out by natural conditions (rain, wind, etc.). Moreover, dusting of a culture medium containing large amounts of organic substances and high nutriments such as wheat bran, etc., can indiscriminately proliferate natural microorganisms and hence in such a case, there is a danger that a large amount of undesired microorganisms are proliferated to cause secondary microorganism contamination. Such a microorganism contamination reduces the exterminating effect to vermin as well as is in a danger of giving bad influences on human bodies, animals and plants.